[Mesa-dev] [PATCH 05/12] i965/fs: Use offset a lot more places

[Jason Ekstrand]

On Fri, Sep 19, 2014 at 5:34 PM, Matt Turner <mattst88 at gmail.com> wrote:

> On Fri, Sep 19, 2014 at 1:10 PM, Jason Ekstrand <jason at jlekstrand.net>
> wrote:
> > We have this wonderful offset() function for advancing registers, but
> we're
> > not using it.  Using offset() allows us to do some sanity checking and
> > avoid manually touching fs_reg::reg_offset.  In a few commits, we will
> make
> > offset do even more nifty things for us.
> >
> > Signed-off-by: Jason Ekstrand <jason.ekstrand at intel.com>
> > ---
> >  src/mesa/drivers/dri/i965/brw_fs.cpp              |  18 +--
> >  src/mesa/drivers/dri/i965/brw_fs_cse.cpp          |  12 +-
> >  src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp |   4 +-
> >  src/mesa/drivers/dri/i965/brw_fs_visitor.cpp      | 137
> ++++++++++------------
> >  4 files changed, 78 insertions(+), 93 deletions(-)
> >
> > diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
> b/src/mesa/drivers/dri/i965/brw_fs.cpp
> > index af8c087..ea91705 100644
> > --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> > +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> > @@ -310,8 +310,8 @@ fs_visitor::VARYING_PULL_CONSTANT_LOAD(const fs_reg
> &dst,
> >           inst->mlen = 1 + dispatch_width / 8;
> >     }
> >
> > -   vec4_result.reg_offset += (const_offset & 3) * scale;
> > -   instructions.push_tail(MOV(dst, vec4_result));
> > +   fs_reg result = offset(vec4_result, (const_offset & 3) * scale);
> > +   instructions.push_tail(MOV(dst, result));
>
> Isn't this going to cause us to copy an fs_reg twice, rather than just
> setting .reg_offset?
>
> I'd like to check the generated code.
>

What's your concern there?  Just that we're useing more CPU?
--Jason
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